N-halamines are a family of compounds characterized by a halogen-nitrogen bond (FIG. 1), formed by the reaction of amines, amides or imides with halogen, hypohalous acid or hypohalite [1]. The nature of the halogen in these compounds is formally positive, and thus they exhibit oxidative properties, similar to hypohalous acids and salts (e.g. hypochlorite bleach, NaOCl). The most stable compounds are chloramines and bromamines, which have exhibited diverse reactions and have been widely used for research and industry, especially in the field of water treatment and disinfection. Lately, halamines were attached to polymers and textile for potential use as water purification systems (columns, filters) and biocidal coatings. The main advantage of N-halamine filters and coatings is the optional regeneration of the N—Cl bond after oxidation of the substrate, by hypochlorite wash. This regeneration, however, is possible only if the N—Cl is not adjacent to a C—H bond, since elimination might occur, resulting in loss of N—H capable of being chlorinated (FIG. 1). N—Cl bond strength, indirectly proportional to active chlorine release, is different among chloramines derived from amines, amides and imides (FIG. 2).
As oxidative antibacterial agents, N-halamines have been widely-used for sanitation of pools, spas and water reservoirs, and as additives in laundry products and dishwasher detergents, of which examples will follow. However, only few of the halamines have been employed for decontamination of chemical warfare agents (CWAs), specifically sulfur mustard (HD) and VX ([S-2-(diisopropylamino)ethyl]-O-ethyl methylphosphonothiolate), which are sensitive to oxidation.
Tetrachlorinated glycolurils have been developed and tested as protection against chemical agents back in the 1950s and 1960s [2], and continue to exhibit interesting results to date, as candidates for sulfur mustard decontamination. A promising candidate, S-330 (FIG. 3), was evaluated as an anti-vesicant additive for a topical skin protectant [3]. Chlorinated hydantoins and imidazolidinones (FIG. 3) were also employed for the decontamination of toxic chemicals, usually evaluated against sulfur mustard simulants [4]. N-chlorosulfonamidates, chloramine-B and chloramine-T, (FIG. 3) were used to oxidize sulfur mustard and VX, as a part of a Soviet personal decontamination kit, adopted later in the American M258 kit. This reaction took place in an aqueous/alcoholic solution containing 5% ZnCl2 to maintain a pH of 5-6 [5]. However, at this low pH, detoxification of G-agents was not efficient. Nowadays, these compounds and their respective dichloramines (a second Cl atom instead of the Na) are used, as a mixture with hexachloromelamine 1 in a Russian decontamination solution for vehicles and terrain. A pool-sanitizing compound, sodium dichloroisocyanurate (NaDCC, FIG. 3) has been employed in CWA decontamination as the active ingredient of various products (Cristanini's BX-24, OWR's 10% NaDCC aqueous solution for terrain decontamination, OWR's BC emulsion and CASCAD). In contrast to former N-halamines, NaDCC is used specifically for terrain rather than personal decontamination [6].
Lately, a comprehensive review of halamines and their applications has been published [7]. Most of the current synthetic efforts in the N-halamine field have been directed at the attachment of N-halamines to insoluble polymers, thus obtaining antibacterial fabrics, active resins, filters and columns suitable for antibacterial water treatment. Decontamination of CWAs and simulants was also addressed by polymeric N-halamines, preferably hydantoins (FIG. 3) attached to fabrics. These studies include grafting of hydantoin monomers on synthetic fibers [8], direct attachment of hydantoin methylols on cotton or cotton/polyester [9] or attachment of hydantoins to cotton via a siloxane bond [10]. Notwithstanding, the majority of polymeric N-halamine products address bacteria and other biological hazards, rather than deal with chemical agent decontamination.
Current decontaminating agents focus on treating the CWA available for decontamination, such as visible droplets on contaminated surfaces. However, a substantial amount of CWA penetrates polymeric surfaces within a short while post contamination (˜30-40% in 30 min). This fraction is not available for destruction by current (mostly aqueous) decontamination agents. Hence, the contaminated polymeric surfaces pose a long-term hazard. Therefore, there is currently a need for novel efficient decontamination agents for CWA and/or biological agent absorbed into polymeric matrices such as paint, coatings, and plastics.
Therefore, it is an object of the present invention to provide novel chemical compounds capable of overcoming the drawbacks of existing decontamination and biocidal agents, and which can be incorporated into polymeric matrices to provide self-decontaminating surfaces. The self-decontaminating surfaces of the invention are capable of both efficiently deactivating any CWA and neutralizing any biological agent which penetrates the surface after exposure.
It is another object of the invention to provide novel decontamination agents that may be advantageously used as additives in various chemical compositions.
It is a further object of the invention to provide processes for manufacturing novel compounds active as decontamination and biocidal agents as well as methods of using the same.
Further purposes and advantages of this invention will appear as the description proceeds.